This invention relates to moving coil assemblies used in, for example, linear motors. In particular, this invention relates to an integrated coil assembly for a linear motor and method for forming the integrated coil.
Existing linear motors typically include wire coils that form magnetic circuits to conduct current and thereby enable such motors to produce a linear force. Generally, the linear force produced is proportional to the current passing through coil windings of the wire coils and magnetic flux density of the magnetic circuits.
As a result of the electrical resistance of such wire coils, the current conducted through the coil windings also generate heat. In some instances, overheating may result when, for example, a large current is required to produce a continuous linear force that is sufficient to move a heavy load. Thus, efficient heat dissipation is necessary to prevent overheating in such instances.
Furthermore, heat may be unevenly generated in existing multi-phase linear motors. Uneven heat generation for a multi-phase linear motor can occur when, for example, a load is maintained at a fixed position at which one or more phases is drawing more current than another one or more phases. This occurs particularly when the load is held in a vertical position against gravity forces. Consequently, the coils of the multi-phase linear motor do not generate heat evenly and any heat generated is also not dissipated evenly.
Reissued U.S. Pat. No. 34,647, issued to Beakley et al on Jul. 26, 1994 and assigned to Trilogy Systems, and U.S. Pat. No. 5,998,890 issued to Sedgewick et al on Dec. 7, 1999 and assigned to Airex Corporation, both describe techniques to improve heat dissipation using improved coil designs. U.S. reissued Pat. No. 34,647 describes separate coils that are placed together to form a coil assembly and use heat-sinking elements, such as an epoxy and an aluminium plate, to dissipate heat. In a similar manner, U.S. Pat. No. 5,998,890 also describes heat-sinking elements for heat dissipation as well as placement of individual coils sequentially offset from adjacent phases to improve heat dissipation.
However, the separate coils in the above prior art coil designs are still subject to uneven heat dissipation in certain circumstances. This is because individual coils are formed separately and then placed sequentially offset from adjacent phases to form a coil assembly. Such placement is difficult to control and, where inaccurate placement occurs, the power output of a multi-phase linear motor using the coil assembly is thus subject to inconsistency and therefore undesirable.
Therefore, a need clearly exists for a coil assembly for multi-phase linear motors that enables a consistent linear force to be provided for different phases and in which heat can be more effectively dissipated.
In accordance with one aspect of the invention, there is disclosed an integrated coil assembly comprising:
a plurality of multi-phase coils, each multi-phase coil having a plurality of coil loops, each coil loop having at least one coil winding and associated with a respective electrical phase,
wherein the plurality of coil loops for different multi-phase coils are interweaved at two opposing portions of the plurality of multi-phase coils to form the integrated coil assembly.
Generally, a coil loop of a subsequent multi-phase coil for conducting current at an electrical phase can be formed adjacent to a coil loop of a preceding multi-phase coil for conducting current at the electrical phase.
More generally, the plurality of coil loops of the integrated coil assembly can have two other opposing portions, the two other opposing portions being substantially parallel to each other.
Optionally, coil loops for each multi-phase coil can have substantially the same coil width relative to each other.
More optionally, coil loops for different multi-phase coils of the integrated coil assembly can have substantially the same coil width relative to each other.
Generally, at each of the two opposing portions, coil loops of a subsequent multi-phase coil can be larger than coil loops of a preceding multi-phase coil.
Optionally, at each of the two opposing portions, coil loops of a subsequent multi-phase coil are larger than coil loops of a preceding multi-phase coil by the thickness of coil windings of the preceding subsequent multi-phase coil.
In accordance with another aspect of the invention, there is disclosed a multi-phase linear motor for producing a linear force, the multi-phase linear motor comprising:
a coil assembly mount having a mounting portion and at least one fin disposed thereon for dissipating heat; and
an integrated coil assembly, mountable to the mounting portion, having:
a plurality of multi-phase coils, each multi-phase coil having a plurality of coil loops, each coil loop having at least one coil winding and associated with a respective electrical phase,
wherein the plurality of coil loops for different multi-phase coils are interweaved at two opposing portions of the plurality of multi-phase coils to form the integrated coil assembly.
Generally, a coil loop of a subsequent multi-phase coil for conducting current at an electrical phase can be formed adjacent to a coil loop of a preceding multi-phase coil for conducting current at the electrical phase.
More generally, the plurality of coil loops of the integrated coil assembly can have two other opposing portions, the two other opposing portions being substantially parallel to each other.
Optionally, coil loops for each multi-phase coil can have substantially the same coil width relative to each other.
More optionally, coil loops for different multi-phase coils of the integrated coil assembly can have substantially the same coil width relative to each other.
Generally, at each of the two opposing portions, coil loops of a subsequent multi-phase coil can be larger than coil loops of a preceding multi-phase coil.
Optionally, at each of the two opposing portions, coil loops of a subsequent multi-phase coil are larger than coil loops of a preceding multi-phase coil by the thickness of coil windings of the preceding subsequent multi-phase coil.
Optionally, the integrated coil assembly can further comprise a molding compound to mold the integrated coil assembly for mounting to the mounting portion.
More optionally, the integrated coil assembly can comprise at least one fin molded from the molding compound.
Further optionally, the integrated coil assembly can comprise at least one groove molded from the molding compound.
Yet more optionally, the integrated coil assembly can comprise molded side edges, the molded side edges being tapered to support air flow.
In accordance with yet another aspect of the invention, there is disclosed a method for forming an integrated coil assembly for a multi-phase linear motor, the integrated coil assembly having a plurality of multi-phase coils, each multi-phase coil having a plurality of coil loops, each coil loop having at least one coil winding and associated with a respective electrical phase, the method comprising the steps of:
(a) winding a first coil loop of a multi-phase coil with a first wire dispenser;
(b) winding another coil loop of the multi-phase coil with another wire dispenser;
(c) repeating the (b) winding another coil loop step, wherein the repeating step is based upon the number of the plurality of coil loops for the multi-phase coil; and
(d) performing steps (a) to (c) for another multi-phase coil of the integrated coil assembly upon completion of the (c) repeating step for the multi-phase coil,
wherein the (d) performing step is based upon the number of the plurality of multi-phase coils required for the multi-phase linear motor.
Generally, the (d) performing step can comprise the step of offsetting position of the another multi-phase coil relative to position of a preceding multi-phase coil.
More generally, the (d) performing step can further comprise the step of winding the another multi-phase coil over the preceding multi-phase coil at two opposing portions.
Still more generally, the (d) performing step can further comprise the step of winding the another multi-phase coil using a winding fixture, the winding fixture being the same for coiling the preceding multi-phase coil.
Optionally, the (a) and (b) winding steps can comprise the step of winding, for each of the coil loops, two opposing portions substantially parallel to each other.
Generally, the (a) and (b) winding steps can comprise the step of winding, for each multi-phase coil, coil loops having substantially the same coil width relative to each other.
More generally, the (a) and (b) winding steps can comprise the step of winding, for different multi-phase coils of the integrated coil assembly, coil loops having substantially the same coil width relative to each other.
Optionally, the method can further comprise the step of molding the plurality of multi-phase coils upon completion of the (d) performing step.
More optionally, the molding step can comprise the step of forming at least one fin with a mold compound.
Still more optionally, the molding step can comprise the step of forming at least one groove between the plurality of multi-phase coils.
Yet more optionally, the molding step can comprise the step of molding at least one mount engagement portion for mounting the integrated coil assembly to a coil assembly mount of the multi-phase linear motor.